Spread of neuroinvasive herpesviruses from sensory neurons to the eye, brain or from mother to newborn are leading causes of morbidity and mortality associated with infections by this class of pathogens. Herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV) are representative members of the two genuses of neuroinvasive herpesviruses (simplexviruses & varicelloviruses), both belonging to the alpha-herpesvirus subfamily. Both viruses establish life-long latent infections in sensory neurons of the peripheral nervous system, and both are established models for use in the laboratory. In this proposal, we leverage our strengths in infectious clone mutagenesis and live-cell viral tracking methods to address the mechanisms of HSV-1 and PRV spread within sensory neurons. Viral transport to the site of latency and transport following reactivation to peripheral innervated tissues are both critical to the viral infectious cycle, and both of these stages of infection are modeled using cultured sensory neurons and examined in animals to investigate the mechanisms of virus intracellular trafficking. In addition, new evidence is provided indicating that the very large herpesvirus tegument protein, VP1/2, is responsible for intracellular transport of capsids, and new tools for dissecting the mechanism of viral transport along microtubules are employed. PUBLIC HEALTH RELEVANCE: Neuroinvasive alpha-herpesviruses are the causative agents of a number of severe diseases including shingles, encephalitis, neonatal infections and herpes keratitis (the leading cause of infectious blindness in the USA and other industrialized nations). This proposal focuses on understanding the cellular mechanisms used by herpesviruses to spread within the nervous system and cause disease, with the long term goal of developing new treatments to intervene with disease progression.